on CompareGMs failure, show link to most recent results on this builder

master/skia_master_scripts/skia_build_step.py

 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """ Skia-specific subclass of BuildStep """
 
 
 from buildbot.status.logfile import STDOUT
 from master.log_parser import retcode_command
 import re
@@ skipping 38 matching lines @@
 
   def IsUploadStep(self):
     return self._is_upload_step
 
   def IsRebaselineStep(self):
     return self._is_rebaseline_step
 
   def commandComplete(self, cmd):
     """ Override of BuildStep's commandComplete method which allows us to parse
     build properties from the output of this step. """
-    if (cmd.rc not in (0, retcode_command.ReturnCodeCommand.RETCODE_WARNINGS)
-        and self._exception_on_failure):
-      raise Exception('Command marked exception_on_failure failed.')
-    if self._get_props_from_stdout and cmd.rc == 0:
+
+    # We make a best effort to parse the properties out of stdout, whether
+    # the command succeeded or failed.  If the command succeeded, we
+    # definitely expect the property to be found in stdout--if not, raise
+    # an exception.
+    if self._get_props_from_stdout:
       log = cmd.logs['stdio']
       stdout = ''.join(log.getChunks([STDOUT], onlyText=True))
       self._changed_props = {}
       for prop, regex in self._get_props_from_stdout.iteritems():
         matches = re.search(regex, stdout)
         if not matches:
-          raise Exception('Unable to parse %s from stdout.' % prop)
+          if cmd.rc == 0:
+            raise Exception('Unable to parse %s from stdout.' % prop)
+          continue
         groups = matches.groups()
         if len(groups) != 1:
-          raise Exception('Multiple matches for "%s"' % regex)
+          if cmd.rc == 0:
+            raise Exception('Multiple matches for "%s"' % regex)
+          continue
         prop_value = groups[0]
         self.setProperty(prop, prop_value, ''.join(self.description))
         self._changed_props[prop] = prop_value
+
+    if (cmd.rc not in (0, retcode_command.ReturnCodeCommand.RETCODE_WARNINGS)
+        and self._exception_on_failure):
+      raise Exception('Command marked exception_on_failure failed.')
     retcode_command.ReturnCodeCommand.commandComplete(self, cmd)
 
   def getText(self, cmd, results):
     """ Override of BuildStep's getText method which appends any changed build
     properties to the description of the BuildStep. """
     text = self.description
     if self._changed_props:
       text.extend(['%s: %s' % (
           key, self._changed_props.get(key)) for key in self._changed_props])
     return text
@@ skipping 27 matching lines @@
   # If this step uploads results (and thus overwrites the most recently uploaded
   # results), only run it on scheduled builds (i.e. most recent revision) or if
   # the "force_upload" property was set.
   if step.IsUploadStep() and \
       not _HasProperty(step, 'scheduler') and \
       not _HasProperty(step, 'force_upload'):
     return False
 
   # Unless we have determined otherwise, run the step.
   return True